S&S was an automobile header manufacturer based out of Newport Beach, CA who branched out into BMX bikes in late 1970's. In 1981 they stopped production altogether 1).
In 1980 they started to ship their 26“ cruisers with 5 speeds (although the pic has a newer derailleur.) It was not a mt. bike but gearing and knobbies on a BMX was a step in the right direction.
1980 S&S Bigfoot 26 https://bmxmuseum.com/bikes/sands/75040/2
[1]. Small numbers from 1980→1981.